Gas turbine engines comprise a number of components that are assembled in series and axially. One the components in this assembly is a compressor that provides high pressure and high temperature fluid such as a gas through a diffuser to a combustor. Compressors are one of the primary components in a gas turbine engine. In designing a gas turbine engine, the operational characteristics of a compressor are of vital importance to the proper and safe operation of the engine. Specifically, the knowledge of certain operational characteristics such as the limits of choke and surge characteristics of the compressor are crucial in preventing stalls, which may result in catastrophic events. Before installing a compressor into a gas turbine engine, each compressor must be tested to make sure that it operates within the intended design limits.
One of the ways to check for the surge and choke values of the compressor is by modulating a variable such as the exhaust fluid flowrate and thereby the backpressure. Traditionally, a butterfly valve has been employed to modulate this variable. However, it has been observed that the butterfly valve system may not provide a robust control system for checking the surge and choke values. Thus there is a need for another valve system to more precisely modulate the exhaust flowrate to better measure the surge and choke values of any desired compressor.